Magnetic field imaging of a driving electric motor using polarized pulsed neutrons at J-PARC/MLF

Hiroi, Kosuke  ; Shinohara, Takenao   ; Hayashida, Hirotoshi*; Parker, J. D.*; Oikawa, Kenichi   ; Harada, Masahide   ; Su, Y. H.  ; Kai, Tetsuya   

We have been developing a quantitative magnetic imaging method using the polarized pulsed neutron beam at MLF of J-PARC. This imaging technique is thought to be a promising method to observe a magnetic field in industrial products under driving states. In our previous work, we demonstrated visualization of ac magnetic field in a solenoid coil using polarized pulsed neutrons. One of the most interesting applications of this method is visualization of dynamic field in an electric motor. In this study, we aimed to apply the ac field imaging technique to a driving electric motor and to clarify the relationship between the magnetic field of a motor and its driving state. In advance, we performed numerical simulation of polarization distributions about the motor. The polarization distribution was confirmed to depend on the composite magnetic fields of the stator and the rotor, and can be used to evaluate rotating state of the motor. In the experiment, we measured temporal changes in the polarization distribution of the driving motor by means of the ac field imaging technique. In this presentation, we explain details of this ac field imaging technique and discuss about experimental results of driving electric motor.